StKnowhere

SchwarzS6

farmerjones

If you are looking for a quality jump starter that has zero safety issues and will last for years, google "Noco". We have a BG70 model on the farm, and have jump-started numerous 9L and 13L diesel engines without issue....all from a handheld device. The quality is pro-grade as well. I can't say enough good things about this brand. We have multiple products of theirs on the farm. I keep a GB40 in my car at all times, always ready to assist someone in need (or myself). Cheap investment on a cold winter night. My family uses these up in Central Alaska as well to jump start cars (-50° F is common, cranks over a cold engine without issue).

halfmanhalftenor

UPDATE on the battery not holding a charge
There appears to be a known issue with a batch of batteries (the large 850Ah ones), whereby they degrade prematurely. When I first phoned Audi up about it, they were struggling to get replacements because they were on back order.
The AA also confirmed that there was a batch of batteries from a particular supplier (used by both Audi and Nissan) that were causing problems. Mine was only holding 330Ah out of 850Ah. This is on a vehicle first registered in the UK Feb 2017.